DES MOINES, Iowa (AP) — Gov. Terry Branstad says that without passage of his property tax plan, residents could see big increases to their tax bills. But a Democratic lawmaker questions the argument.

Branstad, a Republican, on Monday touted his property tax plan, which would gradually reduce taxable assessments for commercial property owners. Branstad says his plan would also limit the amount residential property values could grow, restricting how much those bills could climb.

Branstad unveiled a website with estimates on how much tax bills would rise without passage of his proposal.

The House has approved Branstad’s proposal, but the Senate supports an alternate plan.

Democratic Sen. Joe Bolkcom, of Iowa City, says Branstad is making a “straw argument.” He notes that local government set tax rates, which can be adjusted if values go up.